This invention provides vacuum processing equipment in which workpieces are fed into, through, and out of an evacuated processing chamber on a continuous basis. More generally, the invention relates to equipment for transferring articles into, through, and from a vacuum chamber or other compartment having a selected atmosphere. The equipment allows the processing chamber to remain continuously under the selected vacuum or other atmosphere, while articles are conveyed into and out of it.
Prior evacuated processing equipment has the problem of maintaining the processing chamber under vacuum while feeding fresh workpieces into it and removing the processed ones. One solution is to operate on a batch basis, but this requires that the machine be shut down, with loss of vacuum and with possible contamination of the processing chamber, to load in a new batch of pieces and to remove the batch of processed pieces. Also, these machines have an excessive volume, for storing the batches of workpieces, which must be evacuated after each load/unload interruption. Other prior vacuum processing equipment uses a continuous conveyer within the processing chamber and separate feed and discharge conveyers. The transfer of workpieces between the conveyers requires careful synchronization, otherwise workpieces do not transfer properly. This malfunction generally requires that the machine be shut down, with the loss of vacuum. The prior art has also used a single rotary conveyer operating within a vacuum chamber and which loads and unloads workpieces through an air lock. The circular construction and rotary operation of this machine, however, have been found to be disadvantageous.
Accordingly, it is an object of this invention to provide equipment for the continuous processing of workpieces under a selected atmosphere during the feed and the discharge of workpieces.
Another object is to provide equipment of the above character which avoids multiple-conveyer synchronizing problems attendant with the prior art.
A further object of the invention is to provide equipment of the above character and which has a single drive mechanism for moving workpieces between stations in both the processing and the terminal chambers.
It is also an object to provide equipment of the foregoing character that has a relatively small processing chamber volume that has to be maintained under the selected atmosphere.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention is described herein with particular reference to a vacuum system, but features of the invention apply equally to other equipment wherein articles are processed under a selected non-environmental atmosphere.